On Tue, Sep 13, 2016 at 10:18 PM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > On Tue, Sep 13, 2016 at 06:45:00PM +0900, Byungchul Park wrote: >> Currently, x86 implementation of save_stack_trace() is walking all stack >> region word by word regardless of what the trace->max_entries is. >> However, it's unnecessary to walk after already fulfilling caller's >> requirement, say, if trace->nr_entries >= trace->max_entries is true. >> >> I measured its overhead and printed its difference of sched_clock() with >> my QEMU x86 machine. The latency was improved over 70% when >> trace->max_entries = 5. > > This code will (probably) be obsoleted soon with my new unwinder. Hello, You are right. I also think this will probably be obsoleted with yours. So I didn't modify any details of the patch. I will take your comment into account if it becomes necessary. Anyway, crossrelease needs this patch to work smoothly. That's only reason why I included this patch in the thread. Thank you, Byungchul > Also, my previous comment was ignored: > > Instead of adding a new callback, why not just check the ops->address() > return value? It already returns an error if the array is full. > > I think that would be cleaner and would help prevent more callback > sprawl. > > -- > Josh -- Thanks, Byungchul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>